There is growing belief among employers and health plans that wellness programs represent an important tool to increase access to preventive services and promote healthy behavior. Of particular interest is how financial incentives can be incorporated into these programs to further encourage health promotion and prevention. We propose to study the effects of financial incentives to promote preventive care and wellness by examining recent programs offered by large firms that provide insurance coverage through the same large health insurer. This quasi-experiment affords the opportunity to study wellness programs in the context of actual firm offerings rather than in controlled laboratory environments with limited external validity. Early wellness programs offered by the health insurer included health risk assessments in combination with wellness coaching programs and disease management programs (standard wellness). Subsequently, the health insurer introduced wellness programs that combine the standard wellness offerings with on-site biometric screening and financial incentives that are explicitly tied to actions taken on the part of enrolles to improve health (wellness+financial incentive). Across firms there is natural variation in the size and type of these financial incentives. Our study will take advantage of the natural experiment provided by the insurer's introduction of the wellness+financial incentive program. We will empirically estimate the propensity of these wellness+financial incentive programs, as well as the structure of their financial incentives, to affect rates of health risk assessment, preventive services utilization, and health-promoting behaviors. We propose a multi-year study where we observe enrollees before and after they are offered the new wellness+financial incentive programs, as well as enrollees who are offered standard wellness programs. Through this unique quasi-experimental design our research can guide financial incentives design to enhance wellness programs and improve health promotion and prevention activities. The recent health care reform law (the Patient Protection and Affordable Care Act) explicitly promotes health plan wellness programs. This study can inform whether wellness programs offered with monetary rewards for health actions yield greater success in promoting preventive care than those offered without. Further, it can inform how to structure incentives for wellness programs to encourage greater participation.